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Maize (Zea mays L.) is an important food crop with a wide range of uses in both industry and agriculture. Drought stress during its growth cycle can greatly reduce maize crop yield and quality. However, the molecular mechanisms underlying maize responses to drought stress remain unclear. In this work, a WRKY transcription factor-encoding gene, ZmWRKY30, from drought-treated maize leaves was screened out and characterized. ZmWRKY30 gene expression was induced by dehydration treatments. The ZmWRKY30 protein localized to the nucleus and displayed transactivation activity in yeast. Compared with wild-type (WT) plants, Arabidopsis lines overexpressing ZmWRKY30 exhibited a significantly enhanced drought stress tolerance, as evidenced by the improved survival rate, increased antioxidant enzyme activity by superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), elevated proline content, and reduced lipid peroxidation recorded after drought stress treatment. In contrast, the mutator (Mu)-interrupted ZmWRKY30 homozygous mutant (zmwrky30) was more sensitive to drought stress than its null segregant (NS), characterized by the decreased survival rate, reduced antioxidant enzyme activity (SOD, POD, and CAT) and proline content, as well as increased malondialdehyde accumulation. RNA-Seq analysis further revealed that, under drought conditions, the knockout of the ZmWRKY30 gene in maize affected the expression of genes involved in reactive oxygen species (ROS), proline, and myo-inositol metabolism. Meanwhile, the zmwrky30 mutant exhibited significant downregulation of myo-inositol content in leaves under drought stress. Combined, our results suggest that ZmWRKY30 positively regulates maize responses to water scarcity. This work provides potential target genes for the breeding of drought-tolerant maize., (© 2024 Scandinavian Plant Physiology Society.)

In plants, expansin genes are responsive to heavy metal exposure. To study the bioremediary potential of this important gene family, we discovered a root-expressed expansin gene in sorghum, SbEXPA11, which is notably upregulated following cadmium (Cd) exposure. However, the mechanism underlying the Cd detoxification and accumulation mediated by SbEXPA11 in sorghum remains unclear. We overexpressed SbEXPA11 in sorghum and compared wild-type (WT) and SbEXPA11-overexpressing transgenic sorghum in terms of Cd accumulation and physiological indices following Cd. Compared with the WT, we found that SbEXPA11 mediates Cd tolerance by exerting reactive oxygen species (ROS)-scavenging effects through upregulating the expression of antioxidant enzymes. Moreover, the overexpression of SbEXPA11 rescued biomass production by increasing the photosynthetic efficiency of transgenic plants. In the pot experiment with a dosage of 10 mg/kg Cd, transgenic sorghum plants demonstrated higher efficacy in reducing the Cd content of the soil (8.62 mg/kg) compared to WT sorghum plants (9.51 mg/kg). Subsequent analysis revealed that the SbbHLH041 transcription factor has the ability to induce SbEXPA11 expression through interacting with the E-box located within the SbEXPA11 promoter. These findings suggest that the SbbHLH041–SbEXPA11 cascade module may be beneficial for the development of phytoremediary sorghum varieties. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a heavy metal nonessential for plants; this toxic metal accumulation in crops has significant adverse effects on human health. The crosstalk between copper (Cu) and Cd has been reported; however, the molecular mechanisms remain unknown. The present study investigated the function of wheat Cu transporter 3D (TaCOPT3D) in Cd tolerance. The TaCOPT3D transcripts significantly accumulated in wheat roots under Cd stress. Furthermore, TaCOPT3D-overexpressing lines were compared to wildtype (WT) plants to test the role of TaCOPT3D in Cd stress response. Under 20 mM Cd treatment, TaCOPT3D-overexpressing lines exhibited more biomass and lower root, shoot, and grain Cd accumulation than the WT plants. In addition, overexpression of TaCOPT3D decreased the reactive oxygen species (ROS) levels and increased the active antioxidant enzymes under Cd conditions. Moreover, the transcription factor (TF) TaWRKY22, which targeted the TaCOPT3D promoter, was identified in the regulatory pathway of TaCOPT3D under Cd stress. Taken together, these results show that TaCOPT3D plays an important role in regulating plant adaptation to cadmium stress through bound by TaWRKY22. These findings suggest that TaCOPT3D is a potential candidate for decreasing Cd accumulation in wheat through genetic engineering. [ABSTRACT FROM AUTHOR]

Wheat is a vital food crop that faces threats from various abiotic and biotic stresses. Understanding the molecular mechanism of cadmium (Cd) resistance can provide valuable insights into the tolerance of wheat. Plant proteins known as Topless/Topless–Related (TPL/TPR) play a role in growth, development, defense regulation, and stress response. In this study, we identified TaTPR2 as being induced by Cd stress treatment. Upon Cd treatment, wheat plants overexpressing TaTPR2 exhibited better growth compared to wild–type (WT) plants. Moreover, the transgenic lines showed reduced accumulation of reactive oxygen species (ROS), along with significantly higher activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) compared to WT plants. Additionally, the transgenic lines exhibited lower levels of malondialdehyde (MDA) and electrolyte leakage compared to WT plants. Further analysis revealed that TabHLH41 directly binds to the E–box motif of the TaTPR2 promoter and positively regulates its expression. Overall, the overexpression of TaTPR2 in transgenic wheat resulted in reduced accumulation of Cd and ROS. These findings highlight the significance of the TabHLH41– TaTPR2 pathway as a crucial response to Cd stress in wheat. • The overexpression of TaTPR2 led to a decrease in Cd accumulation in wheat. • The overexpression of TaTPR2 resulted in an enhancement in the capacity to quench ROS under Cd stress. • TabHLH41 binds directly to the promoter of TaTPR2 and upregulates its expression. [ABSTRACT FROM AUTHOR]

Sugar will eventually be exported transporter (SWEET) protein involved in various developmental and stress responses in plants. Here, we report the mechanisms and transcriptional regulatory pathway of the wheat TaSWEET14 in response to cadmium stress. Overexpression of TaSWEET14 improves cadmium stress tolerance and decreases cadmium accumulation in wheat grains. The overexpression of TaSWEET14 in wheat seedlings altered the expression pattern of the ion transporter genes NRAMP5 , LCT1 , HMA3 , and IRT1. These genes were remarkably down-regulated in shoot tissues of TaSWEET14 transgenic wheat lines under cadmium stress. However, there was no significant difference in their expression levels in roots between the wild type (WT) and transgenic plants. In addition, the transgenic plants had a strong ability to remove reactive oxygen species and showed increased activity of antioxidant enzymes. Notably, the transgenic lines had significantly lower cellulose content but higher lignin content than the WT under cadmium stress. The cell wall cadmium content was also significantly higher in the transgenic lines. Lastly, we revealed that TaMYB41 binds directly to the promoter of TaSWEET14 to activate its transcription. This study describes a novel cadmium-responsive regulatory pathway in wheat and demonstrates that TaSWEET14 directly controls wheat cadmium accumulation by altering lignin content. • Overexpression of wheat (Triticum aestivum) SWEET14 (TaSWEET14) significantly improves resistance to cadmium. • Overexpression of TaSWEET14 in wheat resulted in a change of the contents of lignin and cellulose. • Transcription factor TaMYB41 regulates TaSWEET14 gene transcription. [ABSTRACT FROM AUTHOR]

ABSTRACT Wheat is a crucial food crop, yet its production is continually threatened by abiotic stresses, particularly salt stress. Understanding the molecular mechanisms by which wheat responds to salt stress is essential for developing salt‐tolerant varieties. In this study, we investigated the molecular pathway involving the wheat TaDHN7 in response to salt stress. The overexpression of TaDHN7 enhances salt tolerance and reactive oxygen species (ROS) scavenging in wheat, while the knockout of TaDHN7 significantly impairs salt tolerance. Furthermore, we identified that TaWRKY44 promotes the expression of TaDHN7 by binding to the W‐box within the TaDHN7 promoter. Additionally, TaWRKY17 interacts with TaWRKY44, and this interaction enhances the protein stability of TaWRKY44 under salt stress, thereby enhancing its transcriptional regulatory capacity on TaDHN7. This study elucidates the TaWRKY17‐TaWRKY44‐TaDHN7 pathway in response to salt stress in wheat, providing valuable insights for the development of salt‐tolerant wheat cultivars. [ABSTRACT FROM AUTHOR]

In plants, high–affinity potassium transporters (HKTs) not only play a significant role in potassium transport but may also be important for the abiotic stress response. However, information regarding the response of HKTs to cadmium (Cd) stress is limited. Here, we focus on SbHKT2b , the expression of which is highly induced by Cd exposure. SbHKT2b overexpression reduced the accumulation of Cd and increased tolerance to Cd exposure, while SbHKT2b –RNA interference (RNAi) lines exhibited the opposite phenotype. In addition, the overexpression of SbHKT2b resulted in reduced reactive oxygen species (ROS) accumulation and enhanced ROS quenching capacity under Cd stress. Further analyses revealed that SbWRKY54 directly binds to the SbHKT2b promoter and upregulates its expression. Overall, the overexpression of SbWRKY54 decreased Cd and ROS accumulation in transgenic sorghum. Taken together, our results showed that SbWRKY54– SbHKT2b is an important Cd stress response pathway in sorghum. • SbHKT2b overexpression reduced the accumulation of Cd and increased tolerance to Cd exposure. • The overexpression of SbHKT2b resulted in reduced ROS accumulation and enhanced ROS quenching capacity under Cd stress. • SbWRKY54 directly binds to the SbHKT2b promoter and upregulates its expression. • SbWRKY54– SbHKT2b is an important Cd stress response pathway in sorghum. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a toxic heavy metal that poses a serious threat to crop safety, productivity, and human health. Aegilops tauschii is the D genome donor of common wheat and shows abundant genetic variation. However, the tolerance of Ae. tauschii toward Cd at the molecular level is poorly understood. In this study, key factors involved in the Cd stress response of Ae. tauschii were investigated by RNA sequencing. Differentially expressed genes (DEGs) under Cd stress were identified in Ae. tauschii roots and shoots. A Fe(II)/2-oxoglutarate dependent dioxygenase (designated as AetSRG1), with an unknown function in Cd stress, was of particular interest. The open reading frame of AetSRG1 was cloned and overexpressed in wheat, which resulted in reduced Cd accumulation along with a lower Cd2+ flux, decreased electrolyte leakage, and higher reactive oxygen species production. The protein of AetSRG1 interacted with phenylalanine ammonia lyase (PAL). Finally, we found that AetSRG1 stabilizes PAL and promotes the synthesis of endogenous salicylic acid. This study provides novel insights into the molecular mechanisms underlying the response of Ae. tauschii toward Cd stress. The key genes identified in this work serve as potential targets for developing low cadmium wheat. [Display omitted] • Transcriptome profiling reveals key genes involved in Cd response progress of Aegilops tauschii. • A novel stress resistance gene AetSRG1 is identified for Aegilops tauschii Cd tolerance. • Transgenic wheat expressing AetSRG1 showed low cadmium accumulation. • AetSRG1 prevents the degradation of phenylalanine ammonia lyase and programmed cell death. [ABSTRACT FROM AUTHOR]